Although all of the generating plants in Korea are owned by KEPCO subsidiaries, there has been a merchant electricity price market with bidding for many years. The website for the South Korean merchant market looks like it reports hourly prices and I have some old hourly prices, but I had a bit of trouble retrieving the old prices. At any rate, the monthly prices are instructive in evaluating the prices in the comparative USD/MWH.
Studying the market also demonstrates that as with so many other markets in the world, the natural gas price is highly correlated with electricity prices.
http://epsis.kpx.or.kr/epsis/ekmaStaticMain.do?cmd=004013&flag=&locale=EN
Korea Month by Month.xlsx
Prices SMP&BLM – Value of Plants.zip